U.S. patent number 10,983,029 [Application Number 16/154,133] was granted by the patent office on 2021-04-20 for engine misfire detection.
This patent grant is currently assigned to GM GLOBAL TECHNOLOGY OPERATIONS LLC. The grantee listed for this patent is GM Global Technology Operations LLC. Invention is credited to David J. Brooks, Chen-fang Chang, Jun-mo Kang, Yongjie Zhu.
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United States Patent |
10,983,029 |
Zhu , et al. |
April 20, 2021 |
Engine misfire detection
Abstract
A method of detecting misfire in a combustion engine of a motor
vehicle engine includes measuring a speed of a crankshaft,
calculating a modal coefficient for each cylinder of the combustion
engine, and indicating a misfire for at least one of the cylinders
based on the calculation of the modal coefficients.
Inventors: |
Zhu; Yongjie (Troy, MI),
Kang; Jun-mo (Ann Arbor, MI), Chang; Chen-fang
(Bloomfield Hills, MI), Brooks; David J. (Troy, MI) |
Applicant: |
Name |
City |
State |
Country |
Type |
GM Global Technology Operations LLC |
Detroit |
MI |
US |
|
|
Assignee: |
GM GLOBAL TECHNOLOGY OPERATIONS
LLC (Detroit, MI)
|
Family
ID: |
1000005499942 |
Appl.
No.: |
16/154,133 |
Filed: |
October 8, 2018 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20200110004 A1 |
Apr 9, 2020 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02D
35/023 (20130101); F02D 41/0097 (20130101); F02D
41/222 (20130101); G01M 15/11 (20130101); F02D
2200/1015 (20130101) |
Current International
Class: |
G01M
15/11 (20060101); F02D 35/02 (20060101); F02D
41/22 (20060101); F02D 41/00 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101839807 |
|
Sep 2010 |
|
CN |
|
105264204 |
|
Jan 2016 |
|
CN |
|
107795379 |
|
Mar 2018 |
|
CN |
|
08270490 |
|
Oct 1996 |
|
JP |
|
Primary Examiner: Hopkins; Brandi N
Claims
What is claimed is:
1. A method of detecting misfire in a combustion engine of a motor
vehicle engine, the method comprising: measuring a speed of a
crankshaft; calculating a deviation for each cylinder of the
combustion engine by subtracting an average ensemble speed for all
of the cylinders from the speed of the crankshaft; calculating a
modal coefficient for each cylinder of the combustion engine from
the deviation for each cylinder; and indicating a misfire for at
least one of the cylinders based on the calculation of the modal
coefficients.
2. The method of claim 1 wherein the speed of the crankshaft is
measured with an encoder.
3. The method of claim 1 wherein the modal coefficient is a first
modal coefficient.
4. The method of claim 3 wherein the standard deviation is
calculated over a predetermined number of engine cycles.
5. The method of claim 4 wherein a misfire is indicated when the
standard deviation of the first modal coefficient exceeds a
threshold for at least one of the cylinders.
6. The method of claim 4 wherein the predetermined number of engine
cycles is greater than about 50.
7. The method of claim 1 wherein measuring the speed of the
crankshaft includes measuring a steady state speed of the
crankshaft.
8. A method of detecting misfire in a combustion engine of a motor
vehicle engine, the method comprising: measuring a speed of a
crankshaft; calculating a deviation for each cylinder of the
combustion engine by subtracting an average ensemble speed for all
of the cylinders from the speed of the crankshaft; calculating a
first modal coefficient for each cylinder of the combustion engine
from the deviation for each cylinder; calculating a standard
deviation of the first modal coefficient of each cylinder;
determining if the standard deviation of the first modal
coefficient of each cylinder exceeds a threshold; and indicating a
misfire for one or more of the cylinders of the standard deviation
of the first modal coefficient of cylinder exceeds the
threshold.
9. The method of claim 8 wherein the speed of the crankshaft is
measured with an encoder.
10. The method of claim 8 wherein the standard deviation is
calculated over a predetermined number of engine cycles.
11. The method of claim 8 wherein measuring the speed of the
crankshaft includes measuring a steady state speed of the
crankshaft.
12. The method of 10 wherein the predetermined number of engine
cycles is greater than about 50.
Description
INTRODUCTION
The present disclosure relates to detecting misfire of a cylinder
in a combustion engine.
Many motor vehicles utilize combustion engines as the primary
component of the propulsion unit for the motor vehicle. Typically,
the combustion engine is a multi-cylinder engine. During the
operation of the engine, one or more cylinders may misfire, which
reduces the power output and efficiency of the engine. Pressure
sensors may be employed to monitor the pressure in each cylinder to
detect misfires and partial burn in the cylinders. Pressure
sensors, however, are quite costly.
Thus, while current methods to detect misfire in a cylinder achieve
their intended purpose, there is a need for a new and improved
system and method for evaluating misfire in a cylinder.
SUMMARY
According to several aspects, a method of detecting misfire in a
combustion engine of a motor vehicle engine includes measuring a
speed of a crankshaft, calculating a modal coefficient for each
cylinder of the combustion engine, and indicating a misfire for at
least one of the cylinders based on the calculation of the modal
coefficients.
In an additional aspect of the present disclosure, the speed of the
crankshaft is measured with an encoder.
In another aspect of the present disclosure, the modal coefficient
is a first modal coefficient.
In another aspect of the present disclosure, the method further
includes calculating a standard deviation for the first modal
coefficients for each cylinder.
In another aspect of the present disclosure, the standard deviation
is calculated over a predetermined number of engine cycles.
In another aspect of the present disclosure, a misfire is indicated
when the standard deviation of the first modal coefficient exceeds
a threshold for at least one of the cylinders.
In another aspect of the present disclosure, the predetermined
number of engine cycles is greater than about 50.
In another aspect of the present disclosure, measuring the speed of
the crankshaft includes measuring a steady state speed of the
crankshaft.
According to several aspects, a method of detecting misfire in a
combustion engine of a motor vehicle engine includes measuring a
speed of a crankshaft, calculating a first modal coefficient for
each cylinder of the combustion engine, and indicating a misfire
for at least one of the cylinders based on the calculation of the
first modal coefficients.
In another aspect of the present disclosure, the speed of the
crankshaft is measured with an encoder.
In another aspect of the present disclosure, the method further
includes calculating a standard deviation for the first modal
coefficients for each cylinder.
In another aspect of the present disclosure, the standard deviation
is calculated over a predetermined number of engine cycles.
In another aspect of the present disclosure, a misfire is indicated
when the standard deviation of the first modal coefficient exceeds
a threshold for at least one of the cylinders.
In another aspect of the present disclosure, the predetermined
number of engine cycles is greater than about 50.
In another aspect of the present disclosure, measuring the speed of
the crankshaft includes measuring a steady state speed of the
crankshaft.
According to several aspects, a method of detecting misfire in a
combustion engine of a motor vehicle engine includes measuring a
speed of a crankshaft, calculating a first modal coefficient for
each cylinder of the combustion engine, calculating a standard
deviation of the first modal coefficient of each cylinder,
determining if the standard deviation of the first modal
coefficient of each cylinder exceeds a threshold, and indicating a
misfire for one or more of the cylinders of the standard deviation
of the first modal coefficient of cylinder exceeds the
threshold.
In another aspect of the present disclosure, the speed of the
crankshaft is measured with an encoder.
In another aspect of the present disclosure, the standard deviation
is calculated over a predetermined number of engine cycles.
In another aspect of the present disclosure, the predetermined
number of engine cycles is greater than about 50.
In another aspect of the present disclosure, measuring the speed of
the crankshaft includes measuring a steady state speed of the
crankshaft.
Further areas of applicability will become apparent from the
description provided herein. It should be understood that the
description and specific examples are intended for purposes of
illustration only and are not intended to limit the scope of the
present disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings described herein are for illustration purposes only
and are not intended to limit the scope of the present disclosure
in any way.
FIG. 1 is a plot of the deviation in engine speed from an ensemble
averaged speed for a four cylinder engine;
FIG. 2 is a plot of the principle modal component coefficients for
each of the four cylinders;
FIG. 3A is plot of the variation of the engine torque;
FIG. 3B is a plot of the first modal coefficients calculated from
the torque variations shown in FIG. 3A;
FIG. 4A is a plot of the crankshaft speed variations of the engine
in accordance with principles of the present disclosure;
FIG. 4B is a plot of the first modal coefficients calculated from
the crankshaft speed variations shown in FIG. 4A;
FIG. 5A is a plot of the engine speed in rpm of an N number of
engine cycles for the normal operation of the four cylinder
engine;
FIG. 5B is a plot the first modal coefficients of each of the four
cylinders based on the variations of the engine speed shown in FIG.
5A;
FIG. 5C is a plot of the standard deviations of the first modal
coefficients shown in FIG. 5B;
FIG. 6A is a plot of the engine speed in rpm of an N number of
engine cycles of the four cylinder engine when there is a
misfire;
FIG. 6B is a plot the first modal coefficients of each of the four
cylinders based on the variations of the engine speed shown in FIG.
6A;
FIG. 6C is a plot of the standard deviations of the first modal
coefficients shown in FIG. 6B; and
FIG. 7 is a flow diagram of a process for detecting misfire in an
engine in accordance with the principles of the disclosure.
DETAILED DESCRIPTION
The following description is merely exemplary in nature and is not
intended to limit the present disclosure, application, or uses.
Referring to FIG. 1, there is shown a plot of the deviation,
.DELTA., of the engine crankshaft speed associated with each
cylinder of a four cylinder engine over a crank angle, .theta., in
degrees. The deviation, .DELTA., for each cylinder 14, 16, 18 and
20 is determined by subtracting the average ensemble speed for all
the cylinders from the measured engine speed associated with each
cylinder.
By utilizing principal component analysis, similar to singular
value decomposition, the data shown in FIG. 1 is decomposed into
linearly uncorrelated signals identified as principle components
through a linear transformation. The most significant mode is the
first principle mode and a first modal coefficient (FMC) is
identified for each cylinder.
Referring to FIG. 2, there is a plot of the modal coefficients,
.beta., vs nodal number, #, for the principle component
coefficients for cylinder 1, 32, cylinder 2, 30, cylinder 3, 28,
and cylinder 4, 34, corresponding respectively to the plots 18, 16,
14, and 20 shown in FIG. 1. As can be readily seen, cylinder 3, 14
has the largest deviation in FIG. 1. This corresponds to the
largest modal coefficient, .beta., of 25 along the plot 28 for a
modal number, #, of 1. Hence, the first modal coefficients are
utilized to determine deviations in the engine crankshaft
speed.
For the sake of comparison, FIG. 3A shows the variation of the
engine torque, T, over the crank angle, .theta.. Normal operation
is identified by the peaks 36, while the misfires are identified by
the reduced peaks in torque 38 and 40. Determination of the first
modal coefficients of the torque variations or deviations is shown
in FIG. 3B as a plot of the first modal coefficients,
.eta..sub..tau., over a number, N, of engine cycles for cylinder 1,
46, cylinder 2, 48, cylinder 3, 44, and cylinder 4, 42. As can be
seen in FIG. 3B, the largest first model coefficients are
associated with the plot 44 for cylinder 3, identifying misfires in
cylinder 3. These misfires correspond to the deviation of the
torque 38 and 40 from the maximum peaks 36.
Referring to FIG. 4A, there is shown the engine speed, S, in rpm
over the crank angle, .theta.. Normal operation is identified by
the peaks 50, while the misfires are identified by the variations
52 and 54 from the peaks 50. Determination of the first modal
coefficients of the speed variations or deviations is shown in FIG.
4B as a plot of the first modal coefficients, .eta..sub.s, over a
number, N, of engine cycles for cylinder 1, 60, cylinder 2, 62,
cylinder 3, 58, and cylinder 4, 56. As can be seen in FIG. 4B, the
largest first model coefficients are associated with the plot 58
for cylinder 3, identifying misfires in cylinder 3. These misfires
correspond to the variation of the speed 52 and 54 from the maximum
peaks 50.
Referring to FIG. 5A, there is shown plot 64 of the engine
crankshaft speed in rpm over N number of engine cycles for the
normal steady state operation of the four cylinder engine. And FIG.
5B shows the first modal coefficients, .eta..sub.s, for the four
cylinders over N number of cycles. Referring further to FIG. 5C,
there is shown the determination of the standard deviation, .mu.,
of the first modal coefficients identified in FIG. 5B for the four
cylinders over N number of cycles. The horizontal line 66 in FIG.
5C identifies a threshold below which indicates normal operation of
the four cylinder engine. Since the standard deviation of the first
modal coefficient for each cylinder is below the threshold 66, FIG.
5C clearly indicates that the engine is operating normally.
Referring now to FIG. 6A, there is shown plot 68 of the engine
crankshaft speed in rpm over N number of engine cycles for the
steady state operation of the four cylinder engine when a cylinder
is misfiring. And FIG. 6B shows the first modal coefficients,
.eta..sub.s, for the four cylinders over N number of cycles.
Referring further to FIG. 6C, there is shown the determination of
the standard deviation, .mu., of the first modal coefficients
identified in FIG. 6B for the four cylinders over N number of
cycles. Again the horizontal line 66 in identifies a threshold
below which indicates normal operation of the four cylinder engine.
Since the standard deviation of the first modal coefficient for one
of the cylinders above the threshold 66, FIG. 6C clearly indicates
that the engine is operating with a misfiring cylinder.
Turning now to FIG. 7, a process 100 is shown how the utilization
of the first modal coefficients enable the determination of if a
cylinder is misfiring. The process 100 begins in step 102. In step
104, steady state engine crankshaft speed is collected, for
example, with an encoder. In step 106, the first modal coefficients
are calculated for each engine cycle for each cylinder. Next, in
step 108, the standard deviation of the first modal coefficients
for each cylinder is calculated. The process 100 then advances to a
step 110, where the process 100 determines if the standard
deviations exceed a threshold for any of the cylinder. If the
standard deviation does not exceed the threshold, the process 100
loops back to step 104. If the standard deviation does exceed the
threshold, the process advances to stop 112, where the process 100
raises a flag for the cylinder with the standard deviation
exceeding the threshold. The process 100 then stops in step
114.
In various arrangements, the aforementioned process is implemented
as an algorithm in a processor such as an electronic control unit
located within the motor vehicle. In particular arrangements, the
algorithm is a software algorithm stored in a non-transitory
computer readable mechanism associated with the electronic control
unit.
A particular benefit of the present disclosure is the utilization
of measuring the engine crankshaft speed to determine if a cylinder
is misfiring, since speed sensors, such as, for example, encoders,
are significantly less expensive than torque sensors. The process
enables a driver of a motor vehicle or a technician providing
maintenance to the motor vehicle to easily identify when the motor
vehicle's engine is not operating properly, for example, by
observing an engine warning light corresponding to step 112 of the
process 100.
The description of the present disclosure is merely exemplary in
nature and variations that do not depart from the gist of the
present disclosure are intended to be within the scope of the
present disclosure. Such variations are not to be regarded as a
departure from the spirit and scope of the present disclosure.
* * * * *